1 . Also called signal topology. Every LAN has a topology, or the way that the devices on a network are arranged and how they communicate with each other. The way that the workstations are connected to the network through the actual cables that transmit data --    the physical structure of the network -- is called the physical topology. The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.

   2 . The physical layout of devices on a network, every LAN  has a topology , or the way that the devices on a network are arranged and how they communicate with each other. The way that the workstations are connected to the network through the actual cables that transmit data -- the physical structure of the network -- is called the physical topology. The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.

   3 . Because multipoint topologies share a common channel, each device needs a way to identify itself and the device to which it wants to send information.  The method used to identify senders and receivers is called addressing. Four types of physical topologies are frequently used in computer networking:

1. Star
 2. Bus
 3. Ring
 4. Hybrid

   4 . All devices are connected to a central hub. Star networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the hub. The main advantages of a star network are that one malfunctioning node doesn't affect the rest of the network, and it's easy to add and remove nodes. All data goes through the central point, which can be equipped with diagnostic devices that make it easy to trouble shoot and manage the network and Hierarchical organization allows isolation of traffic on the channel. This is beneficial when several, but not all, computers place a heavy load on the network. Traffic from those heavily used computers can be separated from the rest or dispersed throughout for a more even flow of traffic.All devices are connected to a central cable called bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks . Ethernet systems use a bus topology . cabling costs are minimized because of the common trunk.

 
   5 . All buses are implemented using electrical cable; usually coax, and the ends of the cable must be terminated with a terminating resistor that matches the impedance of the cable. The terminating resistor prevents data reflections from coming across as data corruption. The bus is considered a multipoint system because all devices tap into the same backbone cable.

  6 . The ring topology is a physical, closed loop consisting of point-to-point links. In the diagram, you can see how each node on the ring acts as a repeater. It receives a transmission from the previous node and amplifies it before passing it on.